Air power wrenches



Jan. 25, 1966 R. H. DE GASTON AIR POWER WRENCHES Filed April 50, 1962 INVENTOR. @aaa/ defiaaaan BY /477'd/VEV Patented Jan. 25, 1966 3,230,839 AIR POWER WRENCH-IE5; Raoul Hugh dc Gaston, 11539 Louise Ava, Lynwood, Calif. Filed Apr. 30, 1962, Ser. No. 191,376 6 Claims. (Cl. 91-50) This. invention relatesv generally to. fluid powered devices and, more specifically, to a novel fluid powered reciprocating motor.

A variety of fluid powered reciprocating motors have been devised in the past. These motors have been employed for various purposes, as, for example, in power tools, such as [power Wrenches, which are intended to reduce labor time and lessen fatigue. Such reduction in labor time and lessening of fatigue are particularly important in commercial applications, like assembly line operations, involving constant repetition of the same operation.

The emstin-g devices of the kind discussed above, and particularly the fluid powered reciprocating motors embodied therein, possess certain deficiencies which this invention seeks to cure. Among these deficiencies are excessive weight, size and air consumption, complexity and resultant high cost, difliculty Oif handling, and excessive operating noise.

It is a general object of this invention to provide an improved fluid powered reciprocating motor of the character described which is not subject to the defects noted above.

Another object of the invention is to provide an improved fluid powered reciprocating motor which is compact, lightweight, requires a minimum rate of operating fluid, is easy to handle and operate, and is relatively simple in construction and economical to. fabricate.

Further objects, advantages, and features of the invention will become readily evident as the description proceeds.

Briefly, the objects of the invention are attained by providing a fluid powered motor including a housing containing a piston. This piston is urged to one end of its cylinder by a spring and is driven in the opposite direction by a pressurized openating fluid, such as air, which enters through a restricted inlet passage in constant communication with said one end of the cylinder.

The operating fluid exhauts from the latter end of the motor cylinder through exahust passage means having an effective area substantially greater than the inlet passage. Normally closing the exhaust passage means is a valve which is abruptly thrust ofl its seat by a spring acting between the valve and piston in response to predetermined movement of the piston under the action of fluid pressure in the cylinder. When the valve unseats, pressure fluid vents from the cylinder more rapidly that it enters the cylinder. The piston then returns under. spring action to reseat the exhaust valve, after which the cycle repeats.

A better understanding of the invention may be had from the iollowing detailed description taken in connection with the attached drawing, wherein:

FIG. 1 is a longitudinal section through a fluid powered reciprocating motor according to the invention;

FIG. 2 is an enlarged section taken on line 2-2 in FIG. 1; and

FIG. 3 is an enlarged section taken on line 3-3 in FIG. 1.

Referring to this drawing, there is illustrated a fluid powered reciprocating motor 10 according to the invention including a housing 12 having. a cylinder 14. In one end of the housing is an inlet passage 18 for connection to a source (not shown) of fluid under pressure for operating the motor. Inlet passage 18 contains a reduced orifice 29 through which the operating fluid is admitted to the adjacent end of the motor cylinder. This orifice restricts the rate of flow of operating fluid to the motor cylinder, for reasons shown later. Surrounding the inner end of the inlet passage 18 is an annular shoulder 22 defining a valve seat. Concentrioally recessed into the annular seating lf-ace 24 of this valve seat is an annular exhaust groove 26. A number of exhaust passages 28 lead from this exhaust-groove to the exterior of the housing 12. A valve disc 30 is engageable with the seating face 24 of the valve seat 22 to seal off the exhaust groove, and thereby the exhaust passages, from the adjacent end of the motor cylinder 14. The total effective area of these exhaust passages is made substantially greater than the effective area of the inlet orifice 20' for reasons to appear presently. Valve disc 30, when thus engaged with the valve seat 22, admits air to the adjacent end of the motor cylinder 14- through ports 32 in the valve disc. These ports are located on a circle of smaller diameter than annular exhaust groove 26, so that valve disc 36 is adapted'to completely cover and seal the groove, as just stated.

Axially movable in the motor cylinder 14 is a piston 34. Piston 34 is firmly affixed to a piston rod 36 and is sealed to the wall of cylinder 14 by seal ring 38. One end of the piston rod 36 extends to the exterior of the motor housing 12 through a bore 46 in the end of the housing remote from the inlet passage 18. The rod is slid-ably guided in this bore. The opposite end of the piston rod projects loosely into the inlet passage 18, downstream of the orifice 20, when the piston occupies its position of FIG. 1. On this latter end of the. piston rod is an annular shoulder 42.

Valve disc 31 is slidable on the piston rod 36 between the piston 34 and the piston rod shoulder 42. Positioned on the rod between the piston and the shoulder 42, and disposed in contact with the adjacent face of the piston, is a resilient bufler ring 44. A coil spring 46 encircles the piston rod between the valve disc and the piston rod shoulder. A spring 48 acts between the motor housing 12 and the piston 34 and urges the piston and its rod 36 to the right in FIG. 1, to the position shown therein, wherein the butter ring 44 engages the valve disc. 36 and presses the latter against its valve seat 22.

In operation of the motor 16*, pressure fluid from the external supply (not shown) enters the motor cylinder 14, to the right of the piston 34 in FIG. 1, through the inlet orifice 20 and finally through the ports 32 in valve disc 30. The pressure of this fluid initially retains the valve disc on its valve seat 22 to close the exhaust passage 23. The pressure of the entering fluid also acts on the piston 34, attached to piston rod 36, and drives the piston and rod to the left in FIG. 1, against the action of the piston return spring 418, which is thereby compressed. During this travel of the piston rod as with the piston 34, valve spring 46 is being compressed. This valve spring is so proportioned that when it is finally compressed to some given length, such as to its sol-id length, i.e., to the length wherein its turns abut. one another, the spring force exerted on the penforated valve disc 30 is suflicient to overcome the fluid pressure force which holds the disc against its seat 22, and the disc is unseated. Up to this point, the fluid pressure in cylinder 14 held the valve disc firmly in place owing to the relieved pressure in the annular groove 26 which is invented to atmosphere through the exhaust passages 28.

At the time of the unseating of valve disc 30, the piston 34 and its rod 36 are retracted to the left in FIG. 1 against the action of the now compressed piston return spring 48. When the valve disc 30 is thrust off its seat by the compressed valve spring 46, the right end of the motor cylinder 14 in FIG. 1 vents to atmosphere through the exhaust passages 28. Since the total efiective area of these exhaust passages is substantially greater than the area otthe inlet orifice, the incoming pressure fluid is throttled as it flows through the orifice and the: pressure in the cylinder drops. The compressed piston return spring 48 now causes piston 34 to return to its starting position. Dining this return of the piston, bufler ring 44 creates a cushioned impact between the piston and the valve disc which returns the latter to its valve seat 22. The incoming pressure fluid which continues toenter through the inlet 18 then again drives the piston 34 and its rod 36 to the left in FIG. 1 to repeat the cycle.

By way of explanation, it is obvious that pressure fluid continues to enter the cylinder 14 through the orifice 20 while the return stroke of the piston 34 is in progress. Owing to the restricted size of the orifice compared to the total effective area of the exhaust passages 28, however, this incoming fluid in no way hinders normal quick return of the piston under the action of its spring 48. Despite this momentary waste of air, the motor consumes but a fraction of the amount of operating fluid consumed by rotary fluid motors, for example.

The present fluid powered reciprocating motor is obviously capable of various applications and uses. For example, the motor may be employed in a wrench for converting the latter to power operation, thereby to reduce the labor time and lessen fatigue involved in wrenching operations.

While the invention has been disclosed in what is presently considered to be its most practical. and preferred form, the invention is not to be limited to the details described and illustrated herein but is rather to be accorded the full spirit and scope of the claims so as to embrace any and all equivalent devices.

What is claimed as new in support of Letters Patent is:

1. A fluid operated power unit comprising:

a body having a cylinder and a fluid inlet passage communicating with one end of said cylinder,

a piston in said cylinder, said piston being movable in one direction in said cylinder by the force of pressure fluid entering through said passage,

means resiliently biasing said piston in the opposite direction in said cylinder,

said body having exhaust passage means opening at one end to said one end of said cylinder and at the other end to the exterior of said body and a valve seat about said one end of said exhaust passage means and facing into said cylinder,

said exhaust passage means having a substantially greater effective cross-sectional area than the minimum cross-sectional area of said inlet passage,

a valve member engageable with and adapted to be held against said seat by fluid pressure in said one end of said cylinder,

means operatively connecting said piston and valve member for positively unseating the latter from said valve seat upon predetermined movement of said piston in said one direction including a spring seating against said member which is compressed during initial movement of said piston in one direction and acts to abruptly thrust the valve member away from said seat when the member is unseated by said connecting means, and

means acting between said piston and valve member for reseating the latter on said valve seat upon movement of the piston in said opposite direction by said piston biasing means, said inlet passage being in constant communication with said cylinder.

2. A power unit according to claim 1 including:

a manual valve in said inlet passage for controlling the admission of pressure fluid to said one end of said cylinder, said piston continuing to reciprocate d in said cylinder as long as said manual valve is retained open to admit pressure fluid to the cylinder.

3. A power unit according to claim 1 wherein:

said valve member reseating means comprises a resilient element between said piston and valve member for absorbing the energy of the piston upon reseating of the valve member on said valve seat.

4. A fluid operated power unit comprising:

a body having a cylinder and a fluid inlet passage communicating with one end of said cylinder,

a piston in said cylinder having a piston rod, said pis ton being movable in one direction in said cylinder by the force of pressure fluid entering through said passage,

means resiliently biasing said piston in the opposite direction in said cylinder,

said body having a wall member at said one end of said cylinder with a central bore receiving one end of said piston rod,

there being exhaust passage means in said wall member opening at one end to said one end of said cylinder and at the other end to the exterior of the body,

said exhaust passage means having a substantially greater effective cross-sectional area than the mini mum cross-sectional area of said inlet passage,

a valve disc slidably mounted on said one end of said piston rod between said piston and wall member, said valve disc being adapted for seating engagement with said wall member about said exhaust passage means to seal the. latter and being adapted to be held against the wall member by fluid pressure in said one end of said cylinder,

means coacting between said one end of said piston rod and valve disc for positively unseating the latter from said wall member upon predetermined movement of said piston in said one direction including a spring seating against said valve disc which is compressed during initial movement of said piston in said one direction and acts to abruptly thrust the valve disc away from the wall member when the valve disc is unseated by said coacting means, and

means acting between said piston and valve disc for reseating the latter on said wall'member upon movement of the piston in said opposite direction by said piston biasing means, said inlet passage being in constant communication with said cylinder.

5. A power unit according to claim 4 wherein:

said wall member has a circular groove about said bore and opening to said one end of said cylinder and said one end of said exhaust passage means opens to said groove, and said valve disc seats against said wall member about said groove'to seal the latter.

6. A power unit according to claim 4 wherein:

said valve disc reseating means comprises a resilient element on said piston rod between said piston and valve disc for absorbing the energy of the piston upon reseating of the valve disc on said wall member.

References (Iited by the Examiner UNITED STATES PATENTS 2,237,563 4/1941 Kraut -50 X 2,508,568 5/1950 Ellison 8158.1 X 2,726,563 12/1955 Blackburn 81 58.1 2,758,569 8/1956 Peterson 81-58.1 X 2,954,715 10/1960 Wycech 8158.1 2,983,172 5/1961 Rasmussen et al 81 58.1

FOREIGN PATENTS 1,054,846 4/1959 1 Germany.

SAMUEL LEVINE, Primary Examiner.

WILLIAM FELDMAN, FRED E. ENGELTHALER, Examiners. 

1. A FLUID OPERATED POWER UNIT COMPRISING: A BODY HAVING A CYLINDER AND A FLLUID INLET PASSAGE COMMUNICATING WITH ONE END OF SAID CYLINDER, A PISTON IN SAID CYLINDER, SAID PISTON BEING MOVABLE IN ONE DIRETION IN SAID CYLINDER BY THE FORCE OF PRESSURE FLUID ENTERING THROUGH SAID PASSAGE, MEANS RESILIENTLY BIASING SAID PISTON IN THE OPPOSITE DIRECTION IN SAID CYLINDER, SAID BODY HAVING EXHAUST PASSAGE MEANS OPENING AT ONE END TO SAID ONE END OF SAID CYLINDER AND AT THE OTHER END TO THE EXTERIOR OF SAID BODY AND A VALVE SEAT ABOUT SAID ONE END OF SAID EXHAUST PASSAGE MEANS AND FACING INTO SAID CYLINDER, SAID EXHAUST PASSAGE MEANS HAVING A SUBSTANTIALLY GREATER EFFECTIVE CROSS-SECTIONAL AREA THAN THE MINIMUM CROSS-SECTIONAL AREA OF SAID INLET PASSAGE, A VALVE MEMBER ENGAGEABLE WITH AND ADAPTED TO BE HELD AGAINST SAID SEAT BY FLUID PRESSURE IN SAID ONE END OF SAID CYLINDER, MEANS OPERATIVELY CONNECTING SAID PISTON AND VALVE MEMBER FOR POSITIVELY UNSEATING THE LATTER FROM SAID VALVE SEAT UPON PREDETERMINED MOVEMENT OF SAID PISTON IN SAID ONE DIRECTION INCLUDING A SPRING SEATING AGAINST SAID MEMBER WHICH IS COMPRESSED DURING INITIAL MOVEMENT OF SAID PISTON IN ONE DIRECTION AND ACTS TO ABRUPTLY THRUST THE VALVE MEMBER AWAY FROM SAID SEAT WHEN THE MEMBER IS UNSEATED BY SAID CONNECTING MEANS, AND MEANS ACTING BETWEEN SAID PISTON AND VALVE MEMBER FOR RESEATING THE LATTER ON SAID VALVE SEAT UPON MOVEMENT OF THE PISTON IN SAID OPPOSITE DIRECTION BY SAID PISTON BIASING MEANS, SAID INLET PASSAGE BEING IN CONSTANT COMMUNICATION WITH SAID CYLINDER. 